Conventionally, a developer cartridge having a toner accommodating chamber for containing toner is detachably attached to an image forming apparatus such as a laser printer.
A filling port for filling toner in the toner accommodating chamber is formed in a casing of the developer cartridge. After filling toner into the toner accommodating chamber through the filling port, a cap is attached to the filling port. The filling port is thus closed so that the toner filled in the toner accommodating chamber will not leak.
The developer cartridge is detached from the image forming apparatus when the toner in the toner accommodating chamber is consumed. The developer cartridge is replaced with another developer cartridge that is filled with toner. In order to recycle the developer cartridge detached from the image forming apparatus, the cap is first detached from the filling port of the developer cartridge. Then, toner is refilled in the developer cartridge. After refilling the toner, the cap is attached again.
For example, Japanese Unexamined Patent Application Publication No. 9-258537 proposes the following method of recycling a developer cartridge: First, a sealing cap that is fixed to a toner filling port is detached. Then, toner is refilled into the toner accommodating chamber through the opened toner filling port. Thereafter, a cap is fixed to the toner filling port. That is, the cap may be bonded to the toner filling port by an adhesive agent, pressingly fitted into the toner filling port, detachably screwed into the toner filling port, or detachably pressingly fitted into the toner filling port via a packing member.
Japanese Unexamined Patent Application Publication No. 9-222839 proposes attaching a closure member to the toner filling port of a toner container in the developer cartridge via ultrasonic welding.